Strand metering means



April 5, 1966 K. c. BRUGGER I 3,243,974

STRAND METERING MEANS Filed Aug. 5, 1964 3 Sheets-Sheet 1 I l O fgio o 02 0g I .l

INVENTOR.

April 5, 1966 K. c. BRUGGER STRAND METERING MEANS 3 Sheets-Sheet 2 Filed Aug. 5, 1964 INVENTOR. 1%6/0'255/2 6 flragge/ M 2 Maw/km April 5, 1966 K. c. BRUGGER 3,243,974

STRAND METERING MEANS Filed Aug. 5, 1964 3 Sheets-Sheet 5 Zia,

United States Patent 0 3,243,974 STRAND METERING MEANS Kenneth C. Brugger, Kenosha, Wis., assignor to Coopers, Incorporated, Kencsha, Wis., a corporation of Wisconsin Filed Aug. 3, 1964, Ser. No. 387,096 7 Claims. (Cl. 6d-132) This invention relates to knitting machines and in particular to the manner of supplying the strands of yarn to the knitting mechanism in a knitting machine.

In conventional knitting machines, the individual strands of yarn are Withdrawn from the yarn supply cones solely by the action of the knitting needles themselves. As a result, the rate at which the yarn is consumed by the knitting needles is distinctly non-uniform, both in time and from one yarn strand to another. Accordingly, the knit fabric tends to be lacking in uniform appearance. Although generally, means are provided for exerting some measure of control over the stitch count that is, the number of stitches per unit length in the knit fabric, it has been difficult to attain a high degree of stitch count uniformity.

In addition, the individual strands of yarn in conventional knitting machines are subjected to a wide range of varying tensile force. In a conventional circular knitting machine for example, the tensile force experienced by the yarn strands may vary from as little as 2 grams to as much as 8 grams during any given interval of time. It has been found that a particularly significant source of such variations in the tensile forces is the decreasing diameter of the yarn supply cone as it is depleted which varies the full force required to withdraw the yarn from the cone. The tendency of the yarn strand to catch momentarily from tirne-to-time as it is withdrawn from the yarn cone also contributes to the variations in tensile forces experienced by the yarn strand. When affected by such factors, the tension conditions in the yarn strands vary both in time and from one yarn strand to another. The result is a lack of uniformity in the knit fabric not only in appearance but also in strength, due largely to variant tensile distortions in the respective yarn strands. Moreover, the wide range in tension which is exerted on the yarn strands is a frequent source of machine stoppage since a rapid acceleration of tensile force will break a yarn strand, requiring that the machine be stopped while the broken ends of the yarn strands are tied.

It should be undestood at the outset that the lack of uniformity in the rate of yarn consumption by the needles and the lack of constant tension experienced by the yarn strands are substantially interrelated problems in conventional knitting machines. The rate of yarn consumption by the knitting needles is aifected by the tensile force exerted on the yarn strands, and the tensile force experienced by the yarn strands is determined in part by the yarn demand exerted by the knitting needles. Various means have been suggested in the prior art to remedy the problems of non-uniformity in the rate of yarn consumption and lack of constant tension experienced by the yarn strands, but, significantly, these suggestions generally go to one problem or the other Without adequately providing for the interrelation of the two problems. Further, the approach in the prior art has generally been one of providing regulating means which act independently with respect to each yarn strand. This approach does not generally alleviate the problem of lack of uniformity among the plurality of yarn strands,

It is a primary object of the present invention to provide a method for feeding yarn to the knitting needles in a knitting machine which produces a knit fabric of uniform appearance and strength and means for implementing this method.

It is an additional object of the present invention to provide means for feeding yarn to the knitting needles in a knitting machine which enhances the stitch count uniformity and accuracy.

It is a further object of the present invention to provide means for simultaneously metering a plurality of yarn strands to the knitting needles in the knitting machine at a uniform rate.

It is still another object of the present invention to provide means for feeding yarn to the knitting needles in a knitting machine which minimizes tensile distortion of the yarn strands by enabling the maintenance of a constant tension in the yarn strands as they are fed to the knitting needles.

It is one more object of the present invention to provide means for furnishing yarn to the knitting needles in a knitting machine which enables the maintenance of both constant tension in the yarn strands and uniform rate of feed of the yarn strands.

A particularly unfortunate ramification of the lack of a uniform rate of yarn consumption and a constant yarn strand tension occurs with respect to circular knitting machines. As is well known to persons skilled in the art, it is a well established practice with circular knitting machines having rotating needle cylinders that the needle cylinders rotate in a clockwise direction, as viewed from above. In circular knitting machines having stationary needle cylinders, the yarn feed structure of the machine rotates, as a matter of practice, in a counterclockwise direction, as viewed from above. Hence, in both types of circular knitting machines the same relative direction of rotation as between the needle cylinder and the yarn feed structure has been established as a matter of practice, and circular knitting machines have long been constructed in accordance with this practice. A type of yarn known as Z twist yarn, indicating the direction of twist of the yarn fibers, has been utilized in such machines in order to minimize any tendency of the yarn to slip off the knitting needles when the yarn strand momentarily goes slack from time-to-time as a result of variation in the tension in the yarn strand. More specifically, the combination of the established relative rotational direction referred to and Z twist yarn results in a tendency for the yarn loop formed by the knitting needle to twist itself onto the knitting needle rather than off. Yarn of opposite fiber twist, known as S twist yarn, has not been used be cause of its converse tendency to slip off the needle in circular knitting machines of conventional relative rotation.

The disadvantage with the practice referred to in the preceding paragraph is that the use of Z twist yarn, although it prevents the yarn strands from slipping off the needle in a conventional knitting machine, imparts an inherent residual twist in the knit fabric which cannot thereafter be entirely removed.

Accordingly, it is a further object of the present invention to provide a method for feeding yarn to the knitting needles in a circular knitting machine of conventional relative rotational direction which enables the use of S wist yarn so as to produce a knit fabric with reduced residual twist.

Briefly described, the present invention includes a method for furnishing a plurality of strands of material to the needles in a circular knitting machine which comprises feeding the plurality of strands to the needles at a uniform rate with each strand under a predetermined condition of constant tension. To achieve this method, there is provided a yarn metering combination which comprises a power-driven pair of spring biased cylindrical feed rolls adapted to engage and feed a plurality of strands of material, means for spacing the strands of material as they pass through the feed rolls, and means for adjusting the tensile force exerted on the respective strands of material by the needles. An additional particular advantage of the yarn metering device is that it is adapted to provide the knitting machine with a capability for knitting strands of different types of material. For example, natural materials such as cotton, wool, and silk may be knit together or with synthetic materials such as rayon, nylon, Orlon, or the like. 7

These and other features and objects of the invention will be apparent upon reading of the particular description with reference to the following drawings.

In the drawings:

FIGURE 1 is an elevational view illustrating the manner in which the knitting needles act to produce a knit fabric in a typical knitting machine.

FIGURE 1A is an enlarged view of a portion of the yarn strand in FIGURE 1 illustrating Z twist yarn.

FIGURE 1B is also an enlarged view of a portion of the yarn strand in FIGURE 1 illustrating S twist yarn.

EGURE 2 is a front elevational view of a circular knitting machine provided with a preferred embodiment of the yarn metering means of the invention.

FIGURE 3 is a cross-sectional view of the yarn metering unit taken at 33 of FIGURE 2.

FIGURE 4 is a fragmented perspective view illustrating the operative combination of the yarn metering unit and the needle demand adjustment means.

FIGURE 5 is a fragmented perspective view illustrating the needle camming means in a conventional knitting machine.

FIGURE 6 is a top plan view of the yarn metering unit with a portion broken away to illustrate the elliptical configuration of the upper and lower groups of guide apertures.

Referring now to FIGURE 1, there are shown four knitting needles, 10a, 10b, 10c and 10d, each in a particular posture in the knitting cycle. As described in a later portion of the specification, the knitting needles are caused to follow the knitting cycle illustrated as they pass over a plurality of cams. In FIGURE 1 the needles should be considered as moving from right to left over the cams as indicated by the arrow. The needle 10d is in a position initially grasping the yarn strand 11 in its hook 12d. In this position the pivotal latch 13d is fully opened. The preceding needle 100 is in a position of downward movement at which the loop in the preceding row of stitches bears against the latch 13c closing it against the tip of the hook 12. The next preceding needle lab has descended to the lowest point in the knitting Cycle at which the hook 12b and the yarn loop grasped thereby have been pulled through the loop in the previous row such that the loop is cast off from the needle 10b. The leading needle 10a is in a position of upward movement in the knitting cycle, moving toward a position in which it will grasp a new strand of yarn. As the needle 19a rises, the loop engaged in the hook 12a slips down the shank 14a, opening the latch 13a and passing over it to engage in the recess 15a in the shank.

It has been found in accordance with the present invention that withthe type of knitting needle action described in the preceding paragraph, if all of the yarn strands are furnished to the needles at a uniform rate and with each under a condition of relatively constant tension, a fabric of uniform appearance and strength is produced. In addition, it will be apparent that with this type of knitting needle action, the Z twist type yarn illustrated in FIG- URE 1A has a tendency to loop onto the needle hook 12 whereas the S twist ty-pe yarn illustrated in FIGURE 1B has a tendency to slip off the needle hook 112 should the yarn strand 11 become momentarily slack. However, it has been found in accordance with the present invention that by following the method referred to, furnishing the yarn to the needles at a uniform rate and under a condition of constant tension, the tendency of the S yarn to slip off the needle hook 12 can be controlled and mini- 4 mized to a degree that the use of S twist yarn in circular machines of conventional rotation is made feasible. As previously mentioned, this is a distinct advantage since S twist yarn knit in a conventional circular knitting machine does not impart as great a residual twist in the fabric as does Z twist yarn.

Referring now to FIGURE 2 there is shown a con ventional circular knitting machine provided with means in accordance with the present invention for accomplishing the method of yarn feed referred to above. The knitting machine includes a plurality of pins 16 to receive the yarn supply cones 17. The pins 16 are mounted on respective spokes 18 which radially extend from a member 19. A post 20 mounted centrally of the member 19 supports a yarn guide assembly 21 which includes guides 22 and 24. The member 19 is supported'by a pair of rods 25 mounted on an annular base 26. The base 26 is provided with three or more supporting legs 27.

Also mounted onthe base Q6 is an annular assembly 2 8 which includes a plurality of yarn guide members 29, one for each distinct yarn strand, and which houses the needle camrning means described in a later portion of this specification. Mounted within the annular 'base 26 is the needle cylinder 31 made visible in FIGURE 2 by breaking away a portion of the annular assembly 28. The needle cylinder 30 is rotated in a clockwise direction (as viewed from above) by a conventional motor drive unit,

31 and appropriate, gearing (not shown). it will he recognized by those skilled in the art, that the elements recited up to this point are commonly found in conventional circular knitting machines of the rotating needle cylinder type.

Further provided in the knitting machine of FIGURE 2 is a yarn metering unit '32 centrally hung in a fixed position from the post 20. Referring now additionally to FIGURES 3 and 4, the yarn metering unit '32 comprises a housing 34 in which is mounted a power-driven pair of feed rolls 35 and 36 which are surfaces with resilient material such as rubber. The feed roll 35 is secured on a center shaft 37 which, in turn, is mounted in a pair of bearings 35a. The bearings 35:: are respectively afiixed in a pair of blocks 3511 which are respectively mounted in the sidewall slots =33 in the housing 34 so as to abut against the front edges 33a of the slots 33. The shaft 37 extends outwardly from one side of the housing 34 and has aflixed thereon an adjustable pulley '38. The pulley 3 8 is driven by a belt 3-9 from a belt drive assembly 40. The belt drive assembly 49, in turn, is powered by the drive unit 31 through appropriate gearing (not shown). The feed roll 36 is an idling feed roll having a center shaft 41 mounted for rotation in bearings 41a. The bearings 411a are respectively secured in a pair of blocks 4117 which, in turn, are slidably mounted in the sidewall slots 33 for movement, as indicated by the arrow 33b. The idler feed roll 35 is caused to normally bear against the feed roll 35- lby the force of the bias springs 42 respectively mounted in the sidewall slots 33. 'A bar 43 disposed across the front of the housing 34 is rigidly affixed to a pair of arm members 44 which, in turn, are pivotally mounted on the: center shaft '37 of the feed roll 35. Mounted on the arm: members 44 are cam rollers 44a which are adapted to bear against the-blocks 4111 when the bar 43- is pulled downwardly, thereby releasing the idler feed roll 36 from engagement with the driven feed roll 35 against the force of the bias springs 42., interrupting the metering of yarn strands. The idler feed roll 36 is locked in the disengaged position when the cam rollers 44a are received in the V-shape grooves 410 in the blocks 41b. It should he noted that with the feed rolls '35 and 36 in motive engagement, the bar 43 is disposed in a position which lim-its access to the upper portion of the feed rolls, thereby providing a safety feature. When the feed rolls 35 and 36 are disengaged, the bar 43 is disposed in lowered position which permits access to the upper portion of the feed rolls.

Attention is directed to the fact that the top plate 34a of the yarn metering unit housing 34 is provided with a plurality of apertures 45 which serve :to guide the respective yarn strands 11 as they enter the yarn metering unit. Similarly, the bottom plate 34b of the housing 34 is provided with a plurality of apertures 47 which serve to guide the yarn strands 11 as they exit from the yarn metering unit. Referring briefly to FIGURE 6, it is seen that both groups of apertures 45 and 47 are preferably arranged in substantially elliptical or similar curvilinear configurations. The apertures 45 and 47 space the yarn strands uniformly between the feed rolls 35 and 36 in order to prevent any interference of one yarn strand with another. It has 'been found that in a circular knitting machine of the type described herein the elliptical arrangements of the apertures 45 and 47 present optimum yarn guide patterns, exerting minimum drag on the yarn strands. It should be understood that other arrangements of the apertures 45 and 47 are possible especially where the yarn metering unit 32 is utilized in a knitting machine other than the circular type.

As illustrated in FIGURES 2 and 4, the yarn strands 1 1, when motively engaged between the feed rolls 35 and 36, are withdrawn from the yarn supply cones and metered at a uniform rate to the knitting mechanism. The knitting mechanism shown is conventional and is shown in fragmented form in FIGURES 4 and 5. As best shown in FIGURE 5, the cyclical or reciprocating movement of the knitting needles is produced by an arrangement of lower cams 48 secured in an annular member 49 aflixed to the base 26 (FIGURE 2) and an arrangement of upper cams 50 intermediately spaced between the lower cams 48. The knitting needles 10 are mounted for vertical movement in a support ring 51 to form the needle cylinder 39. The ring 51 is driven in the requisite clockwise direction by the drive unit 31. Each of the needles =10 is provided with a butt 52. As the support ring 51 rotates, the needles 10 are alternately moved in an upward direction by the cams 48 and in a downward direction by the cams 50. The yarn strands 11 are guided onto the needles 10 'by the guide members 29 which are secured to a fixed annular support member 46. In this manner, the cyclical knitting action earlier described and depicted in FIGURE 1 is effected.

The earns 50 are each aflixed to a vertically disposed member 54, as best shown in FIGURE 4. The member 54, in turn, is provided at its upper end with an outwardly protruding lug 5-5. The lug 5-5 is secured by means of a threaded bolt 56 to a member 57 which, in turn, is rigidly affixed to the base 26. The bolt 56 is adapted to position the lug 55 to bear against a lock spring 58 disposed between the menrber 57 and the lug 55. The vertical position of the cams 50 in relation to the lower earns 48 may be varied by adjustment of the bolts 56. As it is well known, the adjustable cams 50 thereby determine the vertical length of the cyclical knitting stroke of the knitting needles 10. In the conventional circular knitting machine not provided with the yarn metering unit 32, the positioning of the adjustable cams 50 determines the size of the loop formed by the needles and hence the stitch count and the rate at which the yarn is consumed by the needles 14).

It is important to understand that when the knitting machine is provided with the yarn metering unit 32, there is a change in the function provided by the positioning of the adjustable cams 50. The rate at which yarn is fed to the needles is no longer determined by the vertical stroke length of the needles but rather is determined by the yarn metering unit 32 which furnishes the yarn to the needles 10 at a predetermined rate which may be varied by adjustment of the diameter of the pulley 38. Consequently, the stitch count is also largely controlled by the yarn metering unit 32. By way of explanation of this result, attention is directed briefly to FIGURE 1. Since the amount of yarn metered to the nedles 10 is determined and limited by the yarn metering unit 32, the size of the loops formed by the needles 10 are limited. It has been found that the function provided by the positioning of the earns 50 effectively becomes that of enabling a predetermined, substantially constant tension to be set for each yarn strand. Indeed, in practice a substantially constant tension of as little as 1% grams per yarn strand has been found quite workable with this arrangement, reducing needle wear and breakage.

With respect to the matter of constant tension, it should be noted that the feed rolls 35 and 36 etiiciently isolate the portions of the yarn strands 11 on the exit side of the yarn metering unit 32 from the normal causes of tension variance, in particular the changing diameter of the yarn supply cones 17. The resilient surfaces of the feed rolls 35 and 36 absorb the effect of such tension varying causes.

From the foregoing description, it can now be seen that by combining the yarn metering unit 32 with the conventional adjustable cam positioning feature in a conventional knitting machine, a novel result is achieved. All of the yarn strands 11 are fed to the needles 10 at the same uniform rate. Further, the tension on each of the individual yarn strands 11 will be substantially constant and may be adjusted by positioning of the adjustable cams 50. The result of these advantages is to enable the production of evenly knit fabric with high stitch count accuracy and a minimum of knit-ting machine stoppages. An additional salient result is the enablement of the use of S twist yarn in a conventional circular knitting machine.

In passing, it should be noted that the structure of the yarn metering means in a circular knitting machine with a stationary needle cylinder would be quite similar, the primary difference being that the yarn metering unit 32 would rotate in lieu of remaining stationary as in the present embodiment.

Although certain specific embodiments have been used in illustrating the invention along with specific terminology, it is to be understood that this is merely by way of example and in no manner is to be construed as a limitation. It is contemplated that certain modifications may be made within the scope of the claims without departing from the spirit of the invention.

What is claimed is:

1. In a circular knitting machine of the type including a cylindrical arrangement of reciprocating knitting needles which is characterized by a clockwise rotational relationship with respect to the feed of the yarn strands, the method for feeding S twist type yarn to the knitting needles comprising the steps of simultaneously metering a plurality of S twist yarn strands to the cylindrical arrangement of knitting needles having a clockwise rotational relationship with respect to the feed of said S twist yarn strands at a predetermined uniform rate while imposing a condition of relatively constant predetermined tension on each of said S twist yarn strands.

2. In a knitting machine of the type including a cylindrical arrangement of reciprocating knitting needles having a predetermined rotational relationship with respect to the feed of the yarn strands, the method comprising the steps of: simultaneously metering at a predetermined uniform rate to the cylindrical arrangement of knitting needles having a predetermined rotational relationship relative to the direction of feed of the yarn strands, a plurality of yarn strands having a direction of fiber twist such that said yarn strands would normally tend toward twisting ofI of the knitting needles in said cylindrical arrangement under conditions of slack, while imposing a condition of relatively constant predetermined tension on each of said yarn strands.

3. In a circular knitting machine of the type including a cylindrical arrangement of reciprocating knitting needles and means for adjusting the length of stroke of said knitting needles, the combination with said cylindrical arrangement of knitting needles and said stroke adjustment means comprising: a power driven pair of cylindrical feed rolls, said pair of feed rolls motively engaging a plurality of strands of material therebetween for simultaneously metering said plurality of strands of material to said knitting needles at a selected common rate; means for spacing said strands of material in a constant predetermined relationship as said strands of material pass between said pair of feed rolls, said feed rolls and said spacing means being positioned and arranged relative to said cylindrical arrangement of knitting needles such that said plurality of strands of material diverge substantially unimpeded from a straight line array from a pair of feed rolls to a curvilinear array at said cylindrical arrangement of knitting needles; and

means for selecting said common metering rate of said pair of feed rolls, adjustment of said stroke adjustment means in relation to said selected common metering rate enabling the establishment of a relatively constant tension condition in each of said plurality of strands of material.

4. A combination as defined in claim 3 wherein each of said pair of feed rolls is provided with a drive surface of resilient material.

5. The combination defined in claim 3 further comprising: spring means biasing said pair of feed rolls into motive engagement of said strands of material and camrning means for selectively disengaging said pair of opposed feed rolls from said strands of material.

6. In a circular knitting machine including a plurality of reciprocating needles, means for simultaneously metering a plurality of strands of material to said knitting needles at a common predetermined rate comprising: a power driven pair of opposed feed rolls adapted to motively engage said strands of materials; a first plurality of apertures arranged in a substantially elliptical pattern for guiding said strands of material into said pair of feed rolls; and a second plurality of apertures arranged to guide said strands of material as they exit from said pair of feed rolls.

7. In a circular knitting machine including a plurality of reciprocating needles, means for simultaneously metering a plurality of strands of material to said knitting needles at a common predetermined rate comprising: a power dn'ven pair of opposed feed rolls adapted to motively engage said strands of material; a first plurality of apertures arranged to guide said strands of material into said pair of feed rolls; and a second plurality of apertures arranged in a substantially elliptical pattern for guiding said strands of material as they exit from said pair of feed rolls.

References Cited by the Examiner UNITED STATES PATENTS 2,333,705 11/1943 Cooper 66-132 2,941,383 6/1960 Mishcon et al. 6654 X 3,090,215. 5/1963 Rosen 66132 3,123,991 3/ 1964 Schmidt 66-54 FOREIGN PATENTS 861,879 3/1961 Great Britain.

DONALD W. PARKER, Primary Examiner.

RUSSELL C. MADER, P. C. FAW, Assistant Examiners. 

1. IN A CIRCULAR KNITTING MACHINE OF THE TYPE INCLUDING A CYLINDRICAL ARRANGEMENT OF RECIPROCATING KNITTING NEEDLES WHICH IS CHARACTERIZED BY A CLOCKWISE ROTATIONAL RELATIONSHIP WITH RESPECT TO THE FEED OF THE YARN STRANDS, THE METHOD FOR FEEDING S TWIST TYPE YARN TO THE KNITTING NEEDLES COMPRISING THE STEPS OF SIMULTANEOUSLY METERING A PLURALITY OF S TWIST YARN STANDS TO THE CYLINDRICAL ARRANGEMENT OF KNITTING NEEDLES HAVING A CLOCKWISE ROTATIONAL RELATIONSHIP WITH RESPECT TO THE FEED OF SAID S TWIST YARN STRANDS AT A PREDETERMINED UNIFORM RATE WHILE IMPOSING A CONDITION OF RELATIVELY CONSTANT PREDETERMINED TENSION ON EACH OF SAID S TWIST YARN STANDS. 